package com.wenhao.lock;

/**
 * 线程之间的通信问题
 * 线程交替执行 A B 操作同一个变量 num = 0
 * A num + 1
 * B num - 1
 * <p>
 * 通知 等待唤醒
 *
 * @author Wenhao Tong
 * @create 2021-08-19 16:58
 */
public class ProviderAndConsumer {
    public static void main(String[] args) {
        Data data = new Data();

        new Thread(() -> {
            for (int i = 0;i < 10;i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "A").start();
        new Thread(() -> {
            for (int i = 0;i < 10;i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "B").start();
        new Thread(() -> {
            for (int i = 0;i < 10;i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "C").start();
        new Thread(() -> {
            for (int i = 0;i < 10;i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "D").start();
    }
}

class Data {
    private int number = 0;

    public synchronized void increment() throws InterruptedException {
        // 避免虚假唤醒
        while (number != 0) {
            // 等待
            this.wait();
        }
        // 业务
        System.out.println(Thread.currentThread().getName() + "=>" + ++number);
        // 通知
        this.notifyAll();

    }

    public synchronized void decrement() throws InterruptedException {
        // 避免虚假唤醒
        while (number == 0) {
            // 等待
            this.wait();
        }
        // 业务
        System.out.println(Thread.currentThread().getName() + "=>" + --number);
        // 通知
        this.notifyAll();
    }
}
